Catalytic hydrogenation of functionalized amides under basic and neutral conditions

Abstract

A new, base-free high turnover number (TON) catalyst for hydrogenation of simple and functionalized amides is prepared by reacting [Ru(η³-C₃H₅)(Ph₂P(CH₂)₂NH₂)₂]BF₄ and BH₄⁻ under hydrogen. The hydrogenation proceeds with C–N cleavage to form the corresponding amine and alcohol. The base-free and base-promoted hydrogenations tolerate alcohols, amines, aromatic bromides, chlorides and fluorides, ethers, certain olefins, and N-heterocyclic rings. The reaction was used to deprotect the amine groups in certain acetyl amides to form, for example, an N-heterocyclic amine containing an aryl bromide. The base-free system also selectively hydrogenates N-acyloxazolidinones without epimerization at the α-position, and reduced β-lactams to form the corresponding amino alcohols.